Question about GH3 video files

I did an video interview with the GH3 and had the camera recorded non-stop for about 30minutes, the 16gb card's maximum capacity.

I was using a class 10 card and was shooting at 1920x1080, .MOV, 30p, 72Mbps All-Intra.

The camera never stopped recording however it did divide my interview sequentially in four seperate files i.e. once it got to about 4 gb(ish) it continued recording but in another folder. Can someone explain this?

Thanks

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